What are the key considerations in designing post-tensioned concrete systems?

Post-tensioning design considers: (1) Tendon profile optimization - balancing load moments, (2) Prestress losses - friction, wobble, anchorage slip, elastic shortening, creep, shrinkage, relaxation (total 15-25%), (3) Secondary moments from tendon eccentricity at supports, (4) Allowable stresses at transfer and service (different limits), (5) Ultimate strength with stress in tendons calculated from strain compatibility, (6) Anchorage zone reinforcement design, (7) Minimum reinforcement for crack control. Unbonded vs bonded tendons have different ultimate behavior and fire resistance.